void setBatchDeleteMode(bool doBatch)

This method sets a “Batch Delete Mode” on or off, depending on whether doBatch is TRUE or FALSE, respectively.  If  “Batch Delete Mode” is on when deleteByCode is called, the portion of the view under each deleted feature is not redrawn.  Instead, the entire view is redrawn after all features have been deleted.  This approach is preferred when many (perhaps hundreds or thousands) of features are to be deleted at once, because it is very fast.